Hammer drill mechanism

ABSTRACT

A portable electric tool is adapted for drilling or hammerdrilling operations. The hammer-drilling mechanism is simple, reliable, easy to adjust, and facilitates low-cost high-volume manufacture of the tool. Additionally, a two-speed gearing is provided, such that the tool has four modes of operation: lowspeed drilling; low-speed hammer-drilling; high-speed drilling; or high-speed hammer-drilling.

United States Patent Howell Sept. 17, 1974 HAMMER DRILL MECHANISM 3,363,700 1/1968 Bogusch, Jr. 173/109 [751 Inventor: Harold George Howe", Bedfom, 31233333 3/1333 giiii'zifffliijjj ""ijjijiiijiiiflfl/ii England 3,695,365 10/1972 Schadlich 173/109 [73] Assignee: The Black and Decker Manufacturing Company, Towson, Primary Examiner-Benjamin W. Wyche Md. Assistant Examiner-Wesley S. Ratliff, Jr. Attorney, Agent, or Firm--Leonard Bloom; Joseph R. [22] Flled' June 1973 Slotnik; Edward D. Murphy [21] Appl. No.: 374,565

[57] ABSTRACT [30] Forelgn Apphcanml Prom), Dam A portable electric tool is adapted for drilling or ham-- July 13, Great Bl'ltall'l mer driing operations The hammer drilling mecha nism is simple, reliable, easy to adjust, and facilitates [52] US. Cl. 74/22 R, 173/109 ]OW COSt high vo1ume manufacture f the tooL Addi [51] Int. Cl. Fl6h 21/06 tionally, a two speed gearing is provided Such that the of Search 6 48, tool has four modes of operation: low speed low-speed hammer-drilling; high-speed drilling; or [56] References cued high-speed hammer-drilling.

UNITED STATES PATENTS 6/1957 Beeson 74/22 9 Claims, 4 Drawing Figures Pmmmsrrm 31mm sum 1 0r 2 HAMMER DRILL MECHANISM SUMMARY OF THE INVENTION A portable electric tool has two modes of operation,

one for drilling and the other for hammer-drilling. The a tool includes a motor housing, a gear case mounted forwardly of the motor housing, and a gear case cover therebetween, the latter constituting an internal wall in the housing. An axially-retractable spindle has a rearward portion journaled in a bearing in the gear case cover. A stationary hammer member is fixed in this gear case cover, radially of the spindle bearing. A movable hammer member is carried by the spindle, and is provided with notched teeth adapted for ratcheting engagement with corresponding notched teeth on the stationary hammer member during the hammer-drilling mode of operation. A shift member is positioned radially of the stationary hammer member, and a thrust bearing means is provided between the shift member and the movable hammer member. Means including a shift button is provided to rotate the shift member through an angle about the axis of the spindle. Cooperating cam means are formed between the shift member and the gear case cover, such that rotation of the shift member causes an axial translation thereof, thereby moving the movable hammer member out of engagement with the stationary hammer member during the drilling mode of operation.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of the tool, with parts broken away and sectioned to illustrate its mechanism, the latter being adjusted in the hammer-drill mode of operation;

FIG. 2 corresponds to a portion of FIG. 1, but illustrates the mechanism adjusted for the drilling mode of operation;

FIG. 3 is an exploded perspective of the mechanism shown in FIGS. 1 and 2; and

FIG. 4 is a section taken across the lines 4-4 of FIG. 2.

DETAILED DESCRIPTION With reference to FIG. 1, there is illustrated a portable electric tool referred to in the art as a hammerdrill. The tool 10 has a motor housing 11, a gear case 12, and a gear case cover 13 therebetween, the latter constituting an internal wall in the tool housing. Additionally, the hammer-drill has a handle 14, a switch 15 for energizing a motor in the motor housing, and a chuck 16 for receiving a suitable tool bit or other implement. For convenience of illustration, the motor and the tool bit have not been shown.

The motor is provided with an armature shaft 17 journaled in a first sleeve bearing 18 in the gear case cover. A pinion 19 is formed on the armature shaft, and

engages an intermediate gear 20 mounted on an intermediate shaft 21 journaledin the gear case. Intermediate gears 22 and 23 (of different size) are carried by the intermediate shaft, and engage corresponding gears 24 and 25 loosely carried by the spindle 26 on which the chuck is mounted. Each of the gears 24 and 25 is biased towards each other by respective springs 27 and 28, and each of the gears has a notched portion 29 and 30 adapted for clutching engagement with a pin 31 carried by the spindle. Manually-manipulatable adjustment means are provided (not shown) for axially sliding one of the gears (24 or 25) away from the pin, thereby allowing the other gear to engage the pin, and thereby keying the other gear to the spindle. This gear shifting two-speed mechanism is described and claimed in US. Pat. Nos. 3,178,955 and 3,178,956, both issued on April 20, 1965, and both assigned to the assignee of the present invention.

With reference again to FIG. 1, and with further reference to FIGS. 2-4, the spindle is axially retractable and spring-loaded via Belleville springs 26a. Further, the spindle has a rearward portion 26b journaled in a second sleeve bearing 32 mounted in the gear case cover. A stationary hammer member, comprising a flanged bushing 33, is piloted concentrically about the bearing 32 and is fixed within the gear case cover. A movable hammer member 34 is carried by the spindle forwardly of the stationary hammer member. The hammer members have corresponding respective notched teeth 35 and 36, see FIGS. 3 and 4, for ratcheting engagement with respect to each other in the hammerdrilling mode of operation. In usage of the tool, the operator exerts a manual forward bias on the tool implement carried by the chuck; this bias pressure causes the spindle to retract axially within the gear case for ratcheting engagement of the notched teeth on the hammer members, thus providing a hammer-drilling mode of operation.

A shift member constituting a washer 37 is piloted concentrically about the stationary hammer member 33, and has a radially-projecting tang 38 engaged within a transverse slot 39 formed in a shift button 40. The shift button, which may be of suitable molded plastic, is guided for limited alternate rotary movement within an arcuate slot 41, see FIG. 4, formed in the gear case cover between the motor housing and the gear case. Because of the connection between the tang 38 and slot 39, the shift button 40 and shift washer 37 may be rotated conjointly through an angle about the axis of the spindle. A cam surface 42 is formed on the side of the shift washer (confronting the gear case cover) and engages a corresponding cam formation 43, see FIG. 3, on the gear case cover.

Thus, rotation of the shift washer 37 causes an axial translation thereof, forwardly in the gear case cover. Axial movement of the shift washer, through a thrust bearing 44 positioned radially of the movable hammer member, moves the movable hammer member (and spindle) forwardly in the gear case, as shown in FIG. 2. Thus, a ratcheting engagement of the notched hammer teeth on the respective hammer members is precluded, even though the spindle is manually retracted. This is the drilling mode of operation of the tool.

As shown in FIGS. 3 and 4, the shift button 40 has arcuately-spaced respective pockets 45a and 45b adapted to alternately receive respective lugs 46a and 46b cast integrally within the gear case cover. The cooperation therebetween limits the arcuate movement of the shift button and provides a detent-type of snap action to preclude inadvertent movement of the shift button.

As will be appreciated by those skilled in the art, the present invention provides a low-cost, simple, reliable mechanism for a relatively high-volume power tool, which may be conveniently adjusted by the operator for either drilling or hammer drilling. Additionally,

the two-speed gearing provides both low-speed and high-speed operation, such that a total of four distinct modes of operation are provided.

Obviously, many modifications may be made without departing from the basic spirit of the present invention; and accordingly, within the scope of the appended claims, the invention may be practiced other than has been specifically described herein.

1 claim:

1. In a portable hammer-drill, the combination of a spindle journaled in a bearing in a housing, a stationary hammer member comprising a bushing piloted concentrically about the spindle bearing, a movable hammer member carried by the spindle and having notched teeth adapted to engage corresponding notched teeth on the bushing, a shift washer piloted concentrically about the bushing, thrust bearing means between the shift washer and the movable hammer element, a shift button mounted in a slot in the housing for limited alternate rotary movement about the axis of the spindle and connected to the shift washer for conjoint movement therewith, and cooperating cam means between the shift washer and the housing, whereby upon rotary movement of the shift washer, the shift washer moves axially to move the movable hammer member sufficiently away from the stationary hammer member to preclude engagement therebetween.

2. The tool of claim 1, wherein the housing includes a gear case cover having a bearing for journaling the rear portion of the spindle, and wherein the bearing is piloted concentrically within the stationary hammer member fixed in the gear case cover.

3. The tool of claim 1, wherein the housing includes a gear case cover constituting an internal wall of the housing, and wherein the cooperating cam means are formed on the rearward face of the shift washer and the forward face of the gear case cover, respectively.

4. The tool of claim 1, wherein the housing includes a gear case cover having the spindle bearing mounted therein, and wherein an armature shaft is joumaled in a second bearing in the gear case cover, parallel to the axis of the spindle bearing, and wherein drive gearing means is disposed between the armature shaft and the spindle.

5. A portable power tool having two modes of operation, one for drilling and the other for hammer-drilling, selectively, comprising a motor housing, a gear case mounted forwardly of the motor housing, a gear case cover between the gear case and motor housing, an axially-retractable spindle joumaled in the gear case, a stationary hammer member fixed in the gear case cover, a movable hammer member carried by the spindle forwardly of the stationary hammer member, cooperating hammer elements formed on the hammer members, respectively, and adapted to engage each other in the hammer-drill mode of operation, a shift member positioned radially of the stationary hammer member, thrust bearing means between the shift member and the movable hammer member, means to rotate the shift member through an angle about the axis of the spindle, and cooperating cam means formed on the shift member and gear case cover, respectively, whereby rotation of the shift member causes an axial translation thereof, thereby moving the movable hammer member forwardly of the gear case cover, and thereby precluding engagement of the hammer members and the cooperating hammer elements thereof in the drilling mode of operation, said means to rotate the shift member comprising a shift button mounted for alternate pivoted movement in an arcuate slot in the gear case cover, the

shift button having a transverse slot formed therein, and the shift member having a radially-projecting tang received in the transverse slot.

6. The tool of claim 5, including means in the arcuate slot in the gear case cover to limit the alternate pivoted movement of the shift button, and further including means therein for providing a detent snap-action to movement of the shift button.

7. A portable power tool having two modes of operation, one for drilling and the other for hammer-drilling, selectively, comprising a motor housing, a gear case mounted forwardly of the motor housing, a gear case cover between the gear case and motor housing, an axially-retractable spindle joumaled in the gear case, a stationary hammer member fixed in the gear case cover, a movable hammer member carried by the spindle forwardly of the stationary hammer member, cooperating hammer elements formed on the hammer members, respectively, and adapted to engage each other in the hammer-drill mode of operation, a shift member positioned radially of the stationary hammer member, thrust bearing means between the shift member and the movable hammer member, means to rotate the shift member through an angle about the axis of the spindle, and cooperating cam means formed on the shift member and gear case cover, respectively, whereby rotation of the shift member causes an axial translation thereof, thereby moving the movable hammer member forwardly of the gear case cover, and thereby precluding engagement of the hammer members and the cooperating hammer elements thereof in the drilling mode of operation, an armature shaft disposed in the motor housing and having a forward portion joumaled in a second bearing in the gear case cover, and drive gearing means disposed between the armature shaft and the spindle, the drive gearing means including manuallyselectable two-speed gearing, whereby four modes of operation are provided: low-speed drilling; low-speed hammer-drilling; high-speed drilling; and high-speed hammer-drilling.

8. In a portable hammer-drill having a motor housing, a gear case, and a gear case cover therebetween, the gear case cover constituting an internal wall between the motor housing and the gear case, the combination of a stationary hammer member comprising a flanged bushing fixed in the gear case cover, a bearing sleeve piloted concentrically within the flanged bushing, a spindle having a rearward portion joumaled in the bearing sleeve, a movable hammer member carried by the spindle and having notched teeth adapted to engage corresponding notched teeth on the flange of the bushing, a shift washer mounted concentrically of the bushing, means for rotating the shift washer through an angle about the axis of the spindle, means responsive to rotation of the shift washer to separate the corresponding notched teeth sufficiently to preclude their engagement, and detent means cooperating with the gear case cover for retaining the shift washer in a desired adjusted position.

9. In a portable power tool adapted for drilling and hammer-drilling operations, respectively, and having a motor housing, a handle depending from the motor housing and adapted to be gripped by the operator, a motor in the motor housing and a switch on the handle for controlling the energization of the motor, a gear case mounted on the motor housing forwardly thereof, a gear case cover comprising an internal wall between the motor housing and the gear case, the motor having an armature shaft journalled in a bearing in the gear case cover, a spindle journalled in bearings in the gear case, one of the bearings being disposed in the forward portion of the gear case and the other in the gear case cover, a pinion on the armature shaft, gearing means in the gear case between the pinion and the spindle, a stationary hammer member fixed in the gear case cover radially of the spindle bearing, an axially-movable ham mer member carried by the rearward portion of the spindle and confronting the stationary hammer member in the gear case cover, the hammer members having respective teeth adapted to engage each other in the hammer-drilling operation, and means urging the hammer members away from one another, the improvement which comprises a shift member positioned axially between the movable hammer member and the gear case cover, and radially of the hammer teeth, a manually-manipulatable shifting element protruding through the gear case adjacent to the gear case cover for effecting movement of the shift member, and means including a cam formation cast integrally with the gear case cover and cooperating with the shift member for translating movement of the shift member into axial movement of the movable hammer member forwardly of the gear case cover and away from the stationary hammer member fixed therein, thereby precluding engagement of the hammer members in the drilling position. 

1. In a portable Hammer-drill, the combination of a spindle journaled in a bearing in a housing, a stationary hammer member comprising a bushing piloted concentrically about the spindle bearing, a movable hammer member carried by the spindle and having notched teeth adapted to engage corresponding notched teeth on the bushing, a shift washer piloted concentrically about the bushing, thrust bearing means between the shift washer and the movable hammer element, a shift button mounted in a slot in the housing for limited alternate rotary movement about the axis of the spindle and connected to the shift washer for conjoint movement therewith, and cooperating cam means between the shift washer and the housing, whereby upon rotary movement of the shift washer, the shift washer moves axially to move the movable hammer member sufficiently away from the stationary hammer member to preclude engagement therebetween.
 2. The tool of claim 1, wherein the housing includes a gear case cover having a bearing for journaling the rear portion of the spindle, and wherein the bearing is piloted concentrically within the stationary hammer member fixed in the gear case cover.
 3. The tool of claim 1, wherein the housing includes a gear case cover constituting an internal wall of the housing, and wherein the cooperating cam means are formed on the rearward face of the shift washer and the forward face of the gear case cover, respectively.
 4. The tool of claim 1, wherein the housing includes a gear case cover having the spindle bearing mounted therein, and wherein an armature shaft is journaled in a second bearing in the gear case cover, parallel to the axis of the spindle bearing, and wherein drive gearing means is disposed between the armature shaft and the spindle.
 5. A portable power tool having two modes of operation, one for drilling and the other for hammer-drilling, selectively, comprising a motor housing, a gear case mounted forwardly of the motor housing, a gear case cover between the gear case and motor housing, an axially-retractable spindle journaled in the gear case, a stationary hammer member fixed in the gear case cover, a movable hammer member carried by the spindle forwardly of the stationary hammer member, cooperating hammer elements formed on the hammer members, respectively, and adapted to engage each other in the hammer-drill mode of operation, a shift member positioned radially of the stationary hammer member, thrust bearing means between the shift member and the movable hammer member, means to rotate the shift member through an angle about the axis of the spindle, and cooperating cam means formed on the shift member and gear case cover, respectively, whereby rotation of the shift member causes an axial translation thereof, thereby moving the movable hammer member forwardly of the gear case cover, and thereby precluding engagement of the hammer members and the cooperating hammer elements thereof in the drilling mode of operation, said means to rotate the shift member comprising a shift button mounted for alternate pivoted movement in an arcuate slot in the gear case cover, the shift button having a transverse slot formed therein, and the shift member having a radially-projecting tang received in the transverse slot.
 6. The tool of claim 5, including means in the arcuate slot in the gear case cover to limit the alternate pivoted movement of the shift button, and further including means therein for providing a detent snap-action to movement of the shift button.
 7. A portable power tool having two modes of operation, one for drilling and the other for hammer-drilling, selectively, comprising a motor housing, a gear case mounted forwardly of the motor housing, a gear case cover between the gear case and motor housing, an axially-retractable spindle journaled in the gear case, a stationary hammer member fixed in the gear case cover, a movable hammer member carried by the spindle forwardly of the stationary hammer member, cooperating hammer elements formed on the hammer members, respectively, and adapted to engage each other in the hammer-drill mode of operation, a shift member positioned radially of the stationary hammer member, thrust bearing means between the shift member and the movable hammer member, means to rotate the shift member through an angle about the axis of the spindle, and cooperating cam means formed on the shift member and gear case cover, respectively, whereby rotation of the shift member causes an axial translation thereof, thereby moving the movable hammer member forwardly of the gear case cover, and thereby precluding engagement of the hammer members and the cooperating hammer elements thereof in the drilling mode of operation, an armature shaft disposed in the motor housing and having a forward portion journaled in a second bearing in the gear case cover, and drive gearing means disposed between the armature shaft and the spindle, the drive gearing means including manually-selectable two-speed gearing, whereby four modes of operation are provided: low-speed drilling; low-speed hammer-drilling; high-speed drilling; and high-speed hammer-drilling.
 8. In a portable hammer-drill having a motor housing, a gear case, and a gear case cover therebetween, the gear case cover constituting an internal wall between the motor housing and the gear case, the combination of a stationary hammer member comprising a flanged bushing fixed in the gear case cover, a bearing sleeve piloted concentrically within the flanged bushing, a spindle having a rearward portion journaled in the bearing sleeve, a movable hammer member carried by the spindle and having notched teeth adapted to engage corresponding notched teeth on the flange of the bushing, a shift washer mounted concentrically of the bushing, means for rotating the shift washer through an angle about the axis of the spindle, means responsive to rotation of the shift washer to separate the corresponding notched teeth sufficiently to preclude their engagement, and detent means cooperating with the gear case cover for retaining the shift washer in a desired adjusted position.
 9. In a portable power tool adapted for drilling and hammer-drilling operations, respectively, and having a motor housing, a handle depending from the motor housing and adapted to be gripped by the operator, a motor in the motor housing and a switch on the handle for controlling the energization of the motor, a gear case mounted on the motor housing forwardly thereof, a gear case cover comprising an internal wall between the motor housing and the gear case, the motor having an armature shaft journalled in a bearing in the gear case cover, a spindle journalled in bearings in the gear case, one of the bearings being disposed in the forward portion of the gear case and the other in the gear case cover, a pinion on the armature shaft, gearing means in the gear case between the pinion and the spindle, a stationary hammer member fixed in the gear case cover radially of the spindle bearing, an axially-movable hammer member carried by the rearward portion of the spindle and confronting the stationary hammer member in the gear case cover, the hammer members having respective teeth adapted to engage each other in the hammer-drilling operation, and means urging the hammer members away from one another, the improvement which comprises a shift member positioned axially between the movable hammer member and the gear case cover, and radially of the hammer teeth, a manually-manipulatable shifting element protruding through the gear case adjacent to the gear case cover for effecting movement of the shift member, and means including a cam formation cast integrally with the gear case cover and cooperating with the shift member for translating movement of the shift member into axial movement of the movable hammer member forwardly of the gear case cover and away from the stationary hammer member fixed therein, thereby precluding engagement of the hammer members in the drilling position. 